15 research outputs found
A study of dynamics of bitter acids and xanthohumol in hop pellets during storage
ArticleEight varieties of hop pellets were analyzed for the contents of α
-
acids, ß
-
acids and
xanthohumol according to the EBC 7.7 analytical method. The pellets were extracted with
acidified mixture methanol
-
diethylether
and analyzed using HPLC with a diode
-
array detector
and a Nova
-
Pak column C
18
. Four series of analyses were performed: immediately after the
unpacking of the pellets and
then
after five, seven and nine months of storage at 4
°C. According
to the first ser
i
es of analyses, the contents were assayed as following (α
-
acids, ß
-
acids,
xanthohumol resp., all in weight % in pellets): Galaxy (13.4, 8.0, 0.74), Citra (11.1, 3.0, 0.48),
Tradition (8.2, 8.0, 0.58), Cascade (4.5, 5.2, 0.25), Northern Brewer (4.0, 2.9, 0.
37), Sládek (3.5,
4.0, 0.48), Saaz (2.0, 3.4, 0.24), and Triskel (1.7, 3.6, 0.18). According to these results, variety
Galaxy was found as the richest in all three parameters. After nine months of storage at 4
°C, the
weight
loss of α
-
acids ranged from 4.1
% (Citra and Triskel) to 66.4% (Galaxy). The losses of β
-
acids and xanthohumol were less distinctive (from zero to 31.3% and 25.7%, resp.) and indicated
good long storage possibilities of these compounds at convenient conditions (darkness, low
temperature,
elimination of direct influence of oxygen)